Process for decorticating fibrous materials



May 29, 1956 ARMSTRQNG 2,747,232

PROCESS FOR DECORTICATING FIBRO-US MATERIALS Filed July 5, 1952 4Sheets-Sheet l COLE/VCHYMH P/ 7/1 {PHRENCH YMH ENE Y" May 29, 1956 B.ARMSTRONG 2,747,232

PROCESS FOR DECORTICATING FIBROUS MATERIALS Filed July 5, 1952 4Sheets-Sheet 2 INVENTOR. BRUCL' fle/wsma 5 T'TORNE Y" y 1956 B.ARMSTRONG 2,747,232

PROCESS FOR DECORTICATING FIBROUS MATERIALS Filed July 5, 1952 4Sheets-Sheet 5 INVEN TOR. 19/90:: #RW: TAO/V6 May 29, 1956 B. ARMSTRONGPROCESS FOR DECORTICATING FIBROUS MATERIALS 4 Sheets-Sheet 4 Filed July3 INVENTOR.

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PROCESS FOR DEfiORTICATKNG FIERGUS MATERIALS Bruce Armstrong, Saginaw,Mich assignar to Saclrscn (2;; Church Company, Saginaw, Mich acorporation or Michigan Application July 3, 1952, Serial No. 297,078

6 Claims. (Cl. 199) This invention relates to a process fordecorticating fibrous vegetable materials such as flax, bagasse, kenaf,ramie or jute, and particularly to a type thereof which effects suchdecortication by repeated bending of bundles of said fibers at highrates of speed and at high frequencies.

In the presently known processes for separating vegetable fibers fromeach other, and for separating same from the material, usually pith,comprising the heart of stalks containing said fibers, principalreliance is placed upon striking such material a large number of timesper second by blunt instruments wherein the shock of such blows, as in acommon hammer mill, breaks down the structure of the material holdingsaid fibers together and leaves such fibers free to separate. However,such methods also tend to break the fibers themselves, or at leastmaterially to weaken same, due to the pounding thereof and it is desiredto find a method for effecting such fiber separation Without suchundesirable weakening thereof.

Further, in such methods of separating fibers, the material comprisingthe heart of the stalks containing the desired fibers is, particularlyif such material is somewhat dry, so pulverized that it is extremelydifiicult to handle and hence is usually lost. Thus, such material,though often containing valuable elements, and from which such productsas cattle feed may often be advantageously made, is lost and an economicwaste consequently occurs.

The fibers upon which the present process is particularly intended tooperate are those fibers which occur somewhat as a sheath located nearthe surface of a vegetable stalk and surrounding a central zone ofrelatively short fibers constituting the pith. These fibers are commonlytermed bast fibers and are relatively long, flexible and tough. Thefibers constituting the pith, or parenchyma, are relatively short andbrittle, as are also other fibrous layers immediately adjacent to andsurrounding the bast fibers. Therefore, if the vegetable stalk issubjected to rapid and repeated bending, the stresses set up within thestalk will break apart these shorter and more brittle fibers andseparate them from the bast fibers but will not materially affect thebast fibers themselves excepting to separate them from each other. Inthis way, it is possible, by subjecting the vegetable material to rapidand repeated bending to break the bonds that exist between the bastfibers themselves and between the bast fibers and the surroundingshorter fibers, particularly the parenchyma, and convert the vegetablestalk into a mass of substantially unbroken and unshortened bast fibers,wherein each thereof is substantially thoroughly separated from otherbast fibers in the massand is well cleaned of other fibers occurring inthe vegetable stalk, and wherein the pith and other associated fibersare scattered loosely through the mass in a su-fficiently broken andshattered form as to be readily separable by any convenient shaking orblowing methods and yet without the same being so small as to renderthem useless for such by-product purposes as cattle feed.

For the purpose of clarity in reference, the term de- 2,747,232 PatentedMay 29, 1956 corticate will hereinafter be used'to refer to that portionof the process which consists of breaking the bond between the bastfibers themselves and between the bast fibers and the surroundingshorter fibers. The term separation or cleaning will refer to the stepsby which the scattered particles of pith and other short fibers whichare scattered through the fibrous mass at the end of the decorticationprocess are ultimately removed therefrom and the bast fibers obtainedfree and clean of all other materials.

It therefore is an object of this invention to provide a method fordisconnecting from each other the fibers 0f fibrous material,particularly of a cellulosic form, withou unduly weakening or shorteningsaid fibers.

A further object of said invention is to provide a method for breakingthe bond between the bast fibers themselves and between the bast fibersand the adjacent shorter fibers, particularly pith, associatedtherewith, which is particularly adaptable to materials having a centercomposed of relatively short fibers, such as corn stalks, sugar cane,flax and many others.

A further object of the invention is to provide a method for breakingthe bond between the bast fibers themselves and between the bast fibersand the adjacent shorter fibers, particularly pith, associatedtherewith, as aforesaid, which will not unduly pulverize or otherwisecomminute the material comprising the heart of such stalks but ratherwill preserve such heart of material largely in chunks of appreciablesize and thereby render it possible to handle same by mechanicalmethods.

A further object of the invention is to provide a method for breakingthe bond between the bast fibers themselves and between the bast fibersand the adjacent shorter fibers, particularly pith, associatedtherewith, as aforesaid, which has material in the heart thereofcomprising nutrient components and so preserving the physical structureof such heart material sufficiently to make it possible to make animalfood therefrom. I

A further "object of the invention is to provide a method fordecorticating fibers of fibrous materials which will not noticeablyshorten or weaken said fibers.

A further object of the invention is to provide a method, as aforesaid,which method may be carried out by a substantially continuouslyoperating means.

A further object of the invention is to provide a method, as aforesaid,which is capable of being practiced by relatively inexpensive means andyet -means which can handle a large volume of such fibrous material.

Other objects and purposes of the invention will be apparent to personsacquainted with processes of this general type upon a reading of thefollowing specification and inspection of the accompanying drawings.

in the drawings:

Figure 1 represents a side view of a segment of fibrous material whichhas been chopped into a convenient length for handling, such as 2 or 3inches. Fig. la indicates an end view of said segment with the importantparts of the stalk indicated for purposes of reference.

Figure 2 shows a central section of a fiber when same is bent in onedirection.

Figure 3 represents the bundle of fibrous material shown in Figure 2when subjected to bending in the opposite direction.

Figure 4 represents a schematic illustration of a portion of a devicefor'practicing saidrmethod and showing two bundles of fibers therein.

Figure 5 represents a section taken on the line 55 of Figure 4.

Figure 6 is a view in vertical section of a machine capable ofpracticing the process.

Figure 7 is a plan View of one of the rotating plates of said machine.

Figure 8 is a section taken on the line 88 of Figure 7.

Figure 9 is an oblique view of an alternate plate for use with saidmachine and showing in broken lines a bundle of fibers ther eon and twoteeth on the cooperating plate. Figure 10 is a section taken on the line1010 of Figure 9.

Figure 11 shows a central longitudinal section of another machinecapable of carrying out the same process. Figure 12 is a section takenon the line 12-42 of Figure 11.

' General description The method herein disclosed contemplates (1)suspending a bundle of fibrous material in a fluid stream, and while sosuspended therein, (2) contacting thereof by suitably spaced fingerswhich will effect a bending of said bundle and a prompt release thereof,followed by the immediate engagement of said bundle by other fingerswhich again bend and release it, the bending and releasing occurring inprogressively shorter segments of the bundles.

Detailed description In meeting the objectives of the invention,recognition is made of the fact that as an elongated bundle of fibers isbent transversely of the direction of said fibers, said fibers will becaused to slip upon each other and will thereby be caused to separate.So long as the bending is carried out without excessive hammering orbeating, such slippage and consequent separation of fibers can beeffected without seriously damaging or weakening the fibers and, in thecase of materials having a substantial amount of pith, such operationscan be carried out without reducing the pith to unreasonably smallpieces.

Turning now to Figures 1 to 3, it will be well understood that thecentral plane or neutral plane, indicated at 3 will, when the segment issubjected to bending, constitute a neutral plane and will be under nostress at all but that all portions above said neutral plane andindicated by the numeral 1 (Figure 2 only) will be in compression andall portions below said neutral plane indicated by the numeral 2 will bein tension. Further, it will be understood that, considering the portion2 by way of example, the tension stresses will be the greatest at thelower extremity of the section and will progressively diminish to zerotoward the neutral plane 3. Thus, any two radially adjacent fibers lyingbetween the lower extremity 4 and the neutral plane 3 will be underdifferent tensile stress and will therefore have a tendency to slip withrespect to each other. When the fibers are in reverse position (Figure3) the tension and compression stresses will be reversed.

This tendency of radially adjacent fibers to slip with respect to eachother, together with the lesser capacity of the short fibers towithstand tensile stresses as compared to the corresponding capacity ofthe bast fibers indicated at and 16, will tend to break said shortfibers apart in an axial direction and tend to separate them from eachother and from the bast fibers in a radial direction. Thus, repeatedbending of a given fibrous stalk a great many times and in manydifferent directions will result in the short fibers surrounding thebast fibers being broken into relatively small pieces and broken loosefrom said bast fibers. Further, said bast fibers will for the samereasons be thoroughly broken loose from each other.

It will be recognized that as each segment of the vegetable stalk breakslongitudinally in response to the shear forces set up by the bendingthereof, each part thereof then becomes a new bundle to be bent andagain split in the same manner as the original segment.

It will be appreciated, however, that, due to the irregular nature ofmost vegetable products, such cleavage as takes place along any givenlongitudinal plane will not take place uniformly. That is, cleavage willoccur at some points along said plane and at other points the fibers, orthe fibers and pith, will remain fastened together. Therefore, furthersteps must be provided in the process to assure that cleavage occursthroughout the full length of all fibers. This is accomplished byprogressively diminishing the length of the segment subjected tobending. Thus, in the beginning of the process a relatively longsegment, as indicated by A in Figure 3, is subjected to the bendingforce and said length is then progressively iminished to a much shorterlength, as the length 13 which is subjected to bending force near theend of the process. Thus, the shearing stress is placed upon allportions of all of the segments and full separation is attained.

In devising a series of mechanical steps by which this broad process maybe effected automatically, I have provided a first plurality of spacedteeth extending into a zone bounded in any convenient manner and I haveprovided also a second plurality of spaced teeth extending between theteeth of said first plurality of teeth and also within said zone. Bymoving said teeth in opposite directions with respect to each other insaid zone, and by causing said bundles of fiber to move through saidzone transversely to the direction of movement of said teeth in responseto the movement of a fluid therethrough, I am able to suspend saidbundles in said fluid in such positions that as they move through saidzone they will be repeatedly held by two teeth of one set and engagedintermediate said two teeth by a tooth of the other set and therebycaused to bend, as illustrated in Figure 4. As tooth 5 moves in thedirection indicated by the arrow C adjacent same and between the teeth 6and 7 the fiber bundle will be subjected to a sharp bending. When saidtooth 5 moves past said teeth 6 and 7, the fiber bundle will then bereleased and in the turbulence of the fluid stream, resulting from therapid passage of the said teeth through said stream, will be caused tosomewhat rotate on its own axis before again being engaged by the sameor other teeth. The spacing between any pair of said teeth may beprogressively diminished during said process or, if more convenient fromthe standpoint of particular means used, a plurality of teeth may beprovided in which different teeth are provided for carrying out thelatter part of the process than those which initiate it and the teethcarrying out the latter part of the process are spaced more closelytogether than the teeth initiating the process.

Further understanding of the process may be had by reference to onespecific means for practicing same, it being understood, however, thatthis particular means is only illustrative of the process and that theprocess may, as already indicated, be carried out by a variety ofspecific apparatus.

Referring now to Figures 6 and 7, there is shown a device which isdisclosed and described in detail in my co-pending application SerialNo. 204,039, now Patent No. 2,716,926 to which reference is hereby made.However, for the purposes of convenience, a brief description thereofwill be set forth herein. A base 13 supports a lower housing 12 whichsupports a spaced upper housing 11. Depending from the lower housing 12is an internal housing 22 supporting a lower closure plate 24. A hollowboss 19 depends from the lower housing 12 for the reception of the upperend of the sleeve 29 and a hollow boss 34 depends from the lower plate24 for the reception of the lower end of the sleeve 29. Means indicatedgenerally at 23 support the spring 39 by which the sleeve 29 isresiliently supported in a vertically adjustable position. Said sleevein turn supports the bearings 32 and 33 which, in turn, rotatablysupport the shaft 28. Said shaft is driven by any convenient means, asthe sheave 31, and drives a lower rotating plate 57. An uppernon-rotating plate 68 is fastened to the upper housing 11 by anyconvenient means. Each of said plates have teeth thereon extendingtowards the other plate and said teeth closely intermesh with eachother. Said teeth are conveniently provided on inserts which in turn arefastened, as by bolting, to the upper non-rotating plate 68 and to thelower rotating plate 57. For example, the lower insert 66 is fastened tothe lower rotating plate 57 by bolts of which one is shown at 67 (Figure6).

Figure 7 illustrates a plan view of said teeth 72 taken from a portionof the lower rotating insert 66. It is understood that the teeth on theupper plate are similar therewith excepting that their radial spacing issuch as to permit them to enter in between the teeth on the lower plateas shown. Said teeth, as appearing in Figure 7, are relatively large andwidely spaced at the centerward portion thereof and become progressivelysmaller and more closely spaced both radially and circumferentially asthey approach the periphery. Material is fed to said plate through thecentral opening 17 (Figure 6) in the upper housing 11 and after passingbetween said teeth escapes through the opening 13 defined between saidupper and lower housings. The clearance between said teeth is determinedby vertical adjustment of the lower rotating plate 57 and will, ofcourse, be suiiicient that the particular fibers being handled by themachine in a given instance will be merely bent between said teeth andwill not be cut or broken.

in Figure 9 there appears an oblique view of a difierent design for saidplates wherein the teeth constitute a plurality of pegs mounted in saidplates and extending from the opposed surfaces of each thereof towardthe other of said plates. manner, as by welding or as indicated inFigure 10. in this instance, the teeth are all of the same size but theyare so arranged on the plate as to be of substantially diminishingspacing as they progress from the inner portion thereof toward theperiphery.

The vanes 65 (Figure 6) are positioned on the periphery of the lowerrotating plate 57 in order to increase the air flow from the entrance 17to the exit 13 and thereby both improve the strength of the air streamby which the fibrous material is carried through the teeth and effect astrong air stream for carrying said fibrous material away from themachine. It will be recognized that the rapid passage of the severalteeth through the zone between the plates 57 and 63 will effect avigorous turbulence in said air stream which, while not interfering withits radially outward flow, will nevertheless agitate the bundles offiber carried by said fluid stream, keep same in suspension and keepsame in constant motion with respect to each other.

The annular zone bounded on the upper and lower sides by the said platesand beginning at the inner edge 80 of the top non-rotating plate 68 andending at the periphery of said plates thus constitutes the zone inwhich the decortication of the vegetable stalks takes place and hencemay be geferred to as the decorticating Zone.

As fibrous material is received into said machine through the entrance17 and enters into the decorticating zone,,it is first engagedbytheinner rows of teeth, for example, as indicated by the broken linesat 9 in Figure 9. Said fiber bundle is then engaged by a tooth moving intheopposite direction as indicated at 5 in Figures 4 and 9. and thefiber. bundleis caused to bend as the tooth 5 urges it between the teeth6 and 7.

As said fiber bundle is momentarily released after it passes betweenteeth 6 and 7 it will move a short distance toward the periphery of theplates as indicated by the arrow D before being engaged by another setof teeth 25, 26 and 27 and during such movement the turbulence of theair between said plates 57 and 68 will cause it to rotate somewhat onits own axis and thus the next bending thereof may be expected to be ina different direction.

It will be appreciated that the strong air stream thus moving the fibersspirally outwardly will keep them some- The teeth are mounted in anyconvenient 6 what aligned to prevent their becoming entangled upon theseveral teeth.

As said fibers move toward the periphery of the plates and into theregion where the teeth are progressively closer together, it will berecognized that the bending will be imposed over progressively shortersegments of a given fiber bundle and thereby the complete separationabove set forth will be obtained.

However, it is important that the teeth be spaced sufiiciently apartfrom each other that the bundle can pass between same as a bundle andwithout being subjected to transverse cutting or breaking. This isindicated in somewhat an exaggerated manner in Figure 4. By thisproviding of sufiicient space between said teeth to prevent theoccurence of substantial cutting or breaking, the fiber bundles aresubjected to bending only and their length is not thereby impaired.Further, any pith material which may come into the process with thefiber bundles will not be pulverized but will pass through the machinein chunks of substantial size and will thereby be obtained in acondition which is more conducive to easy handling than it would be ifthe pith were pulverized and it will be of more commercial value for avariety of purposes, such as for cattle feed in the case of corn orsugar cane operations.

Turning to Figures 11 and 12 for another type of device for practisingthe process of this invention, there is shown an external cylindricalhousing 35 having a hopper 36 at one end thereof and an outlet 37 atthe' 'surface of the drum 42, of similarly progressively diminishedspacing and extending between the teeth 43. A plurality of air inlets 47are placed substantially opposite to, and around the fullcircumferential extent of, the zone between the cylindrical housing 35and the cylindrical drurn 42. Fan blades 46 are located at the dischargeend of the drum 42. Thus, as fiber bundles to be decorticated areintroduced into the hopper 36 and they are caused to pass from saidhopper through the throat 48, an air stream carries them into thedecorticating zone where they are bent, turned and rebent, and suchbending is carried out with progressively diminishing segments, and arefinally discharged through the opening 37. It will be appreciated that,although an entirely different mechanism is used than that aboveillustrated as preferable, the same process will be carried out.

After the decorticating operations are completed, it is then relativelyeasy to separate the broken particles of pith, and other short fibers,from the mass of bast fibers by any of many conventional steps. Suchcleaning steps will normally involve moving of the mass along aninclined plane and may also include concurrent treatment thereof with aflowing stream of air or water, such as shown in United States PatentNumber 2,200,472. As in conventional practice, agitation may be providedby shaking the screen or by delivering the fluid stream in a pulsatingmanner, the latter also being shown in United States Patent No.2,200,472. Alternatively, the separation may be effected by any of thevarious kinds of pulp screens and screening mechanism illustrated anddescribed between pages 726 and 749 of Pulp and Paper Manufacture,volume I, 1950, McGraw-Hill Book Co., inc, or by any of the well knownforms of rotating inclined screens with counter flowing fluid or byvertical flow air separators of conventional sort as shown in UnitedStates Patent Numbers 1,650,727 or 1,085,921. Where temperature controlof the decorticating process 7 is required, it will, in view of theforegoing, be obviously possible to provide the apparatus illustratedand described above with suitable heat exchange means, such asconventional water jacketing of means defining the decorticatingchamber, through which either hot or cold heat exchange fluid, as water,may be circulated.

Accordingly, I have set forth a process by which the above named objectsand purposes may be carried out. In actual experimentation with a widevariety of vegetable materials, this process has been found to beeffective, 1

forth as illustrative only and that various modifications may be madetherein without departing from the broader aspects thereof and that thehereinafter appended claims should be construed to cover suchmodifications excepting as by their own terms they expressly limitotherwise.

I claim:

1. In a method for decorticating bundles of fibrous vegetable material,which bundles consist of relatively long, flexible and tough fibersbonded together with natural bonding agents, the steps comprising:suspending said bundles independently of each other in a fluid streamand conducting said stream and bundles suspended therein through adecorticating zone; applying a bending moment to said bundles while sameremain suspended in said fluid stream, said bending moment being appliedto said respective bundles over a predetermined length thereof;

repeatedly applying subsequent bending moments to said bundles andprogressively diminishing the distance over which said bending moment isapplied as said fluidsupported bundles move through said decorticatingzone; conducting said fluid and the decorticated material supportedthereby out from said zone.

2. In a method for decorticating bundles of fibrous vegetable material,the steps comprising: suspending said bundles independently of eachother in a fluid stream and conducting said stream and bundles suspendedtherein through a decorticating zone; applying a bending moment to saidbundles while same remain suspended in said fluid stream; said bendingmoment being applied to said bundles over a predetermined lengththereof; repeatedly applying subsequent bending moments to said bundlesand progressively diminishing the distance over which said bendingmoment is applied as said fluid supported bundles move through saiddecorticating zone; creating a turbulence within said fluid andutilizing said turbulence to rotate said bundles on an axissubstantially parallel with the direction of said fibers between saidapplications of bending moment.

3. In a method for decorticating bundles of fibrous vegetable material,the steps comprising: suspending said bundles independently of eachother in a fluid stream and conducting said stream and bundles suspendedtherein' through a decorticating zone; imposing a bending moment uponsaid bundles while suspended in said fluid stream by means projectinginto said zone and engaging said bundles, said bending moment beingapplied over a predetermined length of said fiber bundles; utilizingsaid means for creating a turbulence within said zone whereby to rotatesaid bundles on axes parallel to the length of said fibers; repeatedlyimposing further bending moments upon said fibers, said bending momentsbeing of progressively shorter length as said fibers progress throughsaid zone; conducting said fluid and decorticated fibers supportedthereby out from said zone.

4. In a method for decorticating bundles of fibrous vegetable material,the steps comprising: suspending said bundles independently of eachother in a fluid stream and conducting said stream and bundles suspendedtherein through a decorticating zone; applying a bending moment to saidbundles while same remain suspended in said fluid stream, said bendingmoment being applied to said respective bundles over a predeterminedlength thereof; repeatedly applying subsequent bending moments to saidbundles and progressively diminishing the distance over which saidbending moment is applied as said fluid-supported bundles move throughsaid decorticating zone; conducting fluid and decorticated materialsupported thereby out from said zone; and subsequently separating thebast fibers from the pith fibers.

5. In a method of decorticating bundles of fibrous materials, whichbundles consist of relatively long, flexible and tough fibers bondedtogether with natural bonding agents, said bundles being elongated in anaxial direction, the steps comprising: suspending said bundlesindependently of each other in a fluid stream, passing said stream andbundles suspended therein between a pair of spaced obstacles in adirection generally transverse to a plane including said two obstacles,said obstacles being spaced apart a distance less than the axial lengthof said bundles but greater than a distance that would cause the fibersin said bundles to break, the bundles being disposed in said stream sothat the longitudinal axis thereof is generally transverse to thedirection of travel of said stream when said bundles pass between saidobstacles, said bundles being bent by engaging and passing between saidobstacles without being cut.

6. The method of claim 5, including the step of subsequently passingsaid stream and bundles suspended therein between other pairs of spacedobstacles, said other pairs of obstacles being spaced a progressivelylesser distance apart than said first-named pair of obstacles.

References Cited in the file of this patent UNITED STATES PATENTS443,037 Coles Dec. 16, 1890 1,215,936 Holtzclaw Feb. 13, 1917 1,641,119Cook Aug. 30, 1927 1,802,249 Goldberg Apr. 21, 1931 2,090,925 Wilkinsonet a1 Aug. 24, 1937 2,161,502 Brown June 6, 1939 2,208,287 Cochrane July16, 1940 2,222,793 Burkardt Nov. 26, 1940 2,263,591 Patterson Nov. 25,1941 2,391,977 Johansen Ian. 1, 1946

1. IN A METHOD FOR DECORTICATING BUNDLES OF FIBROUS VEGETABLE MATERIAL,WHICH BUNDLES CONSIST OF RELATIVELY LONG, FLEXIBLE AND TOUGH FIBERSBONDED TOGETHER WITH MATURAL BONDING AGENTS, THE STEPS COMPRISING:SUSPENDING SAID BUNDLES INDEPENDENTLY OF EACH OTHER IN A FLUID STREAMAND CONDUCTING SAID STREAM AND BUNDLES SUSPENDED THEREIN THROUGH ADECORTICATING ZONE; APPLYING A BENDING MOMENT TO SAID BUNDLES WHILE SAMEREMAIN SUSPENDED IN SAID FLUID STREAM, SAID BENDING MOMENT BEING APPLIEDTO SAID RESPECTIVE BUNDLES OVER A PREDETERMINED LENGTH THEREOF;REPEATEDLY APPLYING SUBSEQUENT BENDING MOMENTS TO SAID BUNDLES ANDPROGRESSIVELY DIMINISHING THE DISTANCE OVER WHICH SAID BENDING MOMENT ISAPPLIED AS SAID FLUIDSUPPORTED BUNDLES MOVE THROUGH SAID DECORTICATINGZONE; CONDUCTING SAID FLUID AND THE DECORTICATED MATERIAL SUPPORTEDTHEREBY OUT FROM SAID ZONE.